Configuring BLU Logic 1211 in my Pruis 2010

My Prius 2010 without navigation has a BLU Logic 1211 bluetooth package. This was one of the initial models where it was not integrated into the audio system's display, but instead just had 3 buttons (up, call & down buttons) below & to the right of the steering wheel.

I recently erased its bluetooth pairing with my phone, by holding down the call button for about 15 seconds (till I heard 4 short consecutive beeps). Then, when I tried to pair it again, my phone would ask me for a pin that I had conveniently forgotten.

The manual had no information about this & the information on the internet was skimpy. Finally, here's what I found:

The BLU Logic 1211 is configured with a pin/passkey as "1234". I am not aware of any way to change this, but this one just works.